1. Field of the Invention
The present invention relates to an information recording medium that includes a recording layer directly sandwiched between a pair of resin layers and is constructed so that data can be recorded by deforming at least one of the two resin layers through deformation of the recording layer due to irradiation of laser light for recording data.
2. Description of the Related Art
As one example of this kind of information recording medium, an optical information recording medium disclosed by Japanese Laid-Open Patent Publication No. H09-138972 is known. This optical information recording medium is constructed by forming an intermediate layer, a light absorbing layer, a light reflecting layer, and a protective layer (hereinafter, collectively referred to as “functional layers” when no distinction is required) in that order on a substrate in which pregrooves have been formed with a pitch (track pitch) of around 1.6 μm. In this case, the respective functional layers are formed by sputtering or by spin coating. In this optical information recording medium, the light absorbing layer expands (deforms) due to the laser light used for data recording that is irradiated from the substrate side, and data is recorded by pits being formed due to the intermediate layer or the substrate deforming due to the expansion of the light absorbing layer. When data recorded on the optical information recording medium is reproduced (read), laser light for reproducing data is irradiated from the substrate side and the resulting reflected light is received. In this case, the intensity of the reflected light differs between positions where pits have been formed and other positions, so that it is possible to read recorded data by detecting the intensity of the received reflected light.
However, by investigating the conventional optical information recording medium, the present inventors discovered the following problem. The optical information recording medium includes a large number of functional layers formed by sputtering or spin coating. On the other hand, under present conditions where price competition for information recording media is becoming fierce, it is important to simplify the manufacturing process so as to reduce manufacturing costs. However, when manufacturing the above conventional optical information recording medium, a large number of sputtering or spin coating operations are necessary to form the large number of functional layers described above, and due to such processes, there is the problem that it is difficult to reduce the manufacturing cost.